The present invention relates to a new and improved construction of a contact element or contact element arrangement, preferably a contact bridge member, for an electrical switching device or switchgear.
Generally speaking, the contact element or contact element arrangement for an electrical switching device or switchgear as contemplated by the invention is of the type comprising a support or carrier which is provided at one side or face thereof with at least one contact support or member which is operatively associated with an arc conducting element connected with the support or carrier.
In German Patent Publication No. 2,647,888 there is disclosed in the art a contact bridge member containing a trough or vat-shaped support at which there is affixed an intermediate element or part formed of electrically conductive material. Soldered to such intermediate element are two contact supports. The intermediate element possesses end portions which extend away from the contact supports and bound at the ends of the support or carrier. These end portions serve as arc burn-off pieces or elements.
Apart from the fact that with this construction there is not afforded a rapid migration of the arc base points from the contact supports to the arc burn-off pieces, there additionally prevails the danger that the attachment locations of the contact supports with the intermediate element are attacked by the arcs commutating to the arc burn-off pieces. Consequently, there is appreciably reduced the service life of the contact bridge member.
Additionally, a construction of contact bridge member is known wherein the contact supports are directly applied to the base portion of a substantially U-shaped support or carrier and are electrically conductively interconnected by means of a web. Significant in this regard is German Patent Publication No. 1,175,776. At the ends of the support there are secured thereto arc conducting elements which protrude away from the base portion of the support in the direction of the contact supports. Since such arc conducting elements consist of steel the arc base points migrate more rapidly from the contact surfaces than in the case of the previously explained construction of contact bridge member. Nonetheless, even with this solution there is attacked the connection locations between the contact supports and the support or carrier by the arcs which migrate by means of their base points laterally along the contact supports towards the arc conducting elements or pieces. The thus caused damage, which is especially appreciable in the presence of high cut-off currents, necessitates exchange of the contact bridge member after a relatively short period of use.
Other known constructions of contact elements are exemplified by German Pat. No. 1,202,378, German Pat. No. 2,161,616, German Pat. No. 1,527,353 and German Patent Publication No. 2,928,557.